U.S. patent number 6,780,074 [Application Number 09/797,570] was granted by the patent office on 2004-08-24 for method for manufacturing an image display device.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Toshimichi Ouchi.
United States Patent |
6,780,074 |
Ouchi |
August 24, 2004 |
**Please see images for:
( Certificate of Correction ) ** |
Method for manufacturing an image display device
Abstract
A method for manufacturing an image display device includes
disposing the first substrate, on which conductors and wires
connected to the conductors are formed, on a supporting member and
covering a part of the first substrate with a container to thereby
dispose the conductors within a space formed between the first
substrate and the container. Part of the wires is disposed outside
of the space. The method also includes the steps of providing the
space with a desired atmosphere, applying a voltage to the
conductors through the part of the wires disposed outside of the
space, and connecting a second substrate including an image arming
member via a connecting member to the first substrate, at a region
of the first substrate different from a region where the container
and the first substrate are connected together.
Inventors: |
Ouchi; Toshimichi (Ibaraki,
JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
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Family
ID: |
26586873 |
Appl.
No.: |
09/797,570 |
Filed: |
March 5, 2001 |
Foreign Application Priority Data
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Mar 6, 2000 [JP] |
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2000/061127 |
Feb 23, 2001 [JP] |
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2001/048989 |
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Current U.S.
Class: |
445/24;
438/34 |
Current CPC
Class: |
H01J
9/261 (20130101); H01J 9/38 (20130101); H01J
9/40 (20130101); H01J 31/127 (20130101) |
Current International
Class: |
H01J
9/40 (20060101); H01J 9/38 (20060101); H01J
9/26 (20060101); H01J 9/00 (20060101); H01J
009/24 () |
Field of
Search: |
;445/24,25,50,51
;438/34 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 908 916 |
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Apr 1999 |
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EP |
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7-235255 |
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Sep 1995 |
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JP |
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8-171849 |
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Jul 1996 |
|
JP |
|
11-195374 |
|
Jul 1999 |
|
JP |
|
2000-311594 |
|
Nov 2000 |
|
JP |
|
Primary Examiner: Williams; Joseph
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A method for manufacturing an image display device, said method
comprising the steps of: preparing a first substrate having a first
surface and a second surface facing each other, wherein conductors
and wires connecting the conductors are formed on the first
surface; disposing the first substrate, on a supporting member so
as to fix the second surface to the supporting member; covering a
part of the first surface with a container, for disposing the
conductors into a space formed by the first surface and the
container, wherein a part of each wire is disposed outside of the
space; providing the space formed between the container and the
first surface with a desired atmosphere; applying a voltage to the
conductors through the part of the wires disposed outside of the
space; removing the container from the first surface; and
connecting a second substrate, including an image forming member,
via a connecting member, to a region of the first surface different
from a region of the first surface where the container and the
first surface are connected together.
2. A method according to claim 1, wherein said step of providing
the space with the desired atmosphere includes evacuating the
space.
3. A method according to claim 1, wherein said step of providing
the space with the desired atmosphere includes introducing a gas
into the space.
4. A method according to claim 1, wherein the second surface is
fixed to the supporting member by performing a vacuum attraction of
the second surface to the supporting member.
5. A method according to claim 1, wherein the second surface is
fixed to the supporting member by performing electrostatic
attraction of the second surface to the supporting member.
6. A method according to claim 1, wherein said step of disposing
the first substrate on the supporting member is performed by
disposing a heat conduction member between the first substrate and
the supporting member.
7. A method according to claim 1, wherein said step of applying the
voltage to the conductors includes the step of adjusting a
temperature of the first substrate.
8. A method according to claim 1, wherein said step of applying the
voltage to the conductors includes the step of heating the first
substrate.
9. A method according to claim 1, wherein said step of applying the
voltage to the conductors includes the step of cooling the first
substrate.
10. A method for manufacturing an image display device, said method
comprising the steps of: preparing a first substrate having a first
surface and a second surface facing each other, wherein a plurality
of units including a pair of electrodes connected via a conductive
film and wires connecting the plurality of units are formed on the
first surface; disposing the first substrate on a supporting
member, so as to fix the second surface to the supporting member;
covering a part of the first surface with a container, for
disposing the plurality of units into a space formed by the first
surface and the container, wherein a part of each wire is disposed
outside of the space; providing the space formed between the
container and the first surface with a desired atmosphere;
converting each of the plurality of units into an electron-emitting
device by applying a voltage to the plurality of units through the
part of the wires disposing outside of the space; removing the
container from the first surface; and connecting a second
substrate, including an image forming member, to the first
substrate, via a connecting member, at a region of the first
surface different from a region of the first surface where the
container and the first surface are connected together.
11. A method for manufacturing an image display device, said method
comprising the steps of preparing a first substrate having a first
surface and a second surface facing each other, wherein a plurality
of units including a pair of electrodes connected via a conductive
film, a plurality of x-direction wires connecting the units, and a
plurality of y-direction wires connecting the units are formed on
the first surface; disposing the first substrate on a supporting
member, so as to fix the second surface to the supporting member;
covering a part of the first surface with a container, for
disposing the plurality of units into a space formed by the first
surface and the container, wherein a part of each x-direction wire
and a part of each y-direction wire are disposed outside of the
space; providing the space formed between the container and the
first surface with a desired atmosphere; converting each of the
plurality of units into an electron-emitting device by applying a
voltage to the plurality of units through the part of the plurality
of x-direction wires and the plurality of y-direction wires
disposed outside of the space; removing the container from the
first surface; and connecting a second substrate including an image
forming member to the first substrate via a connecting member, at a
region of the first surface different from a region of the first
surface where the container and first surface are connected
together.
12. A method according to claim 10 or 11, wherein said step of
providing the space with the desired atmosphere includes evacuating
the space.
13. A method according to claim 10 or 11, wherein said step of
providing the space with the desired atmosphere includes
introducing a gas into the space.
14. A method according to claim 10 or 11, wherein the second
surface is fixed to the supporting member by performing a vacuum
attraction of the second surface to the supporting member.
15. A method according to claim 10 or 11, wherein the second
surface is fixed to the supporting member by performing
electrostatic attraction of the second surface to the supporting
member.
16. A method according to claim 10 or 11, wherein said step of
disposing the first substrate on the supporting member is performed
by disposing a heat conduction member between the first substrate
and the supporting member.
17. A method according to claim 10 or 11, wherein the applying of
the voltage includes the step of adjusting a temperature of the
first substrate.
18. A method according to claim 10 or 11, wherein the applying of
the voltage includes the step of heating the first substrate.
19. A method according to claim 10 or 11, wherein the applying of
the voltage includes the step of cooling the first substrate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing an
image display device.
2. Description of the Related Art Conventional electron emitting
devices are generally classified into two types of devices, i.e.,
thermionic cathode type devices and cold cathode type devices. The
cold cathode type devices include field emission type devices,
metal/insulating-layer/metal type devices, surface conduction type
devices and the like.
The surface conduction type electron emitting devices utilize the
phenomenon that electron emission occurs by passing a current in a
direction parallel to the surface of a small-area thin film formed
on a substrate. The assignee of the present application has
provided a large number of proposals with respect to surface
conduction type electron emitting devices having new configurations
and applications thereof. The basic configurations and
manufacturing methods of such devices are disclosed, for example,
in Japanese Patent Application Laid-Open (Kokai) Nos. 7-235255
(1995), 8-171849 (1996), 2000-311594 (2000) and 11-195374 (1999),
and EP-A No. 0908916.
The surface conduction type electron emitting devices have the
feature that a pair of electrodes facing each other, and a
conductive film connected to the pair of electrodes and having a
gap in a part of the film are provided on a substrate.
A carbon film having at least one of carbon and a carbon compound
as a main component is provided in the gap.
By providing a plurality of such electron emitting devices on a
substrate and connecting the devices by wires, an electron source
including a plurality of surface conduction type electron emitting
devices can be manufactured.
By combining the electron source with a phosphor, an image display
device can be formed.
Conventionally, such an electron source and an image display device
are manufactured in the following manner.
In a first manufacturing method, first, a plurality of units, each
including a conductive film and a pair of electrodes connected
thereto, and wires connected to the electrodes are each formed on a
substrate. Then, the entirety of the formed units on the substrate
is placed in a vacuum chamber. After evacuating the vacuum chamber,
a gap is formed in the conductive film of each of the units by
applying a voltage to the unit through external terminals (a
"forming" process). Then, a gag of a carbon compound is introduced
into the vacuum chamber, and a voltage is again applied to each of
the units in this atmosphere through the external terminals. By
this voltage application, a carbon film having at least one of
carbon and the carbon compound as a main component is formed in a
portion including the gap (an "activating" process). As a result,
an electron source is formed having the substrate and the plurality
of electron emitting devices. Then, the panel of an image display
device is manufactured by connecting the electron source and a
substrate on which a phosphor is disposed, with an interval of a
few millimeters provided between those components.
In a second manufacturing method, first, a plurality of units, each
including a conductive film and a pair of electrodes connected
thereto, and wires connected to the electrodes of the plurality of
units are each formed on a substrate. Then, the panel of an image
display device is manufactured by connecting the formed substrate
and a substrate on which a phosphor is disposed, with an interval
of a few millimeters being provided between them. Then, the inside
of the panel is evacuated through an exhaust tube connected to the
panel. Then, a gap is formed in the conductive film of each of the
units by applying a voltage to the unit through external terminals
of the panel (the "forming" process). Then, a gas of a carbon
compound is introduced into the panel through the exhaust tube, and
a voltage is again applied to each of the units in this atmosphere
through the external terminals. By this voltage application, a
carbon film having at least one of carbon and the carbon is
compound as a main component is formed in a portion including the
gap (the "activating" process). As a result, an electron source is
provided having a plurality of electron emitting devices formed on
a substrate.
SUMMARY OF THE INVENTION
In the conventional methods for manufacturing en electron source
and an image display device, the above-described "forming" and
"activating" processes are adopted. However, in the above-described
first manufacturing method, as the size of the electron-source
substrate is larger, a larger vacuum chamber and an evacuation
apparatus having a larger pumping speed are required. In the second
manufacturing method, a long time is required for both evacuation
of a small space within the panel in the "forming" process, and
uniform introduction of the gas used in the "activating" process
into the panel and the succeeding evacuation of the gas.
It is an object of the present invention to provide a method for
manufacturing an electron source and an image display device in
which the speed of the "activating" process is increased and the
uniformity of electron emission characteristics is improved, and
which is suitable for mass production.
It is another object of the present invention to provide an image
display device and a method for manufacturing the same in which an
electron source having excellent electron emission characteristics
can be manufactured, and wherein stable vacuum tightness is
maintained by a substrate having an electron source formed thereon
and a substrate having a phosphor formed thereon, disposed so as to
face the first substrate.
The inventor of the present invention has discovered the following
novel aspects of the invention as a result of keen
investigations.
According to one aspect, the present invention which achieves these
objectives relates to a method for manufacturing an image display
device. The method includes the steps of disposing a first
substrate on a supporting member, the first substrate having
conductors and wires connected to the conductors mounted thereon,
and covering a part of the first substrate with a container to
thereby dispose the conductors within a space formed between the
first substrate and the container. Part of the wires is disposed
outside of the space. The method also includes the steps of
providing the space formed between the container and the first
substrate with a desired atmosphere, applying a voltage to the
conductors through the part of the wires disposed outside of the
space, removing the container from the first substrate, and
connecting a second substrate including an image forming member via
a connecting member, to a region of the first substrate different
from a region where the container and the first substrate were
connected together.
According to another aspect, the present invention which achieves
these objectives relates to another method for manufacturing an
image display device. The method includes a step of disposing a
first substrate on a supporting member, the first substrate having
mounted thereon a plurality of units and wires connecting the
plurality of units. Each unit includes a pair of electrodes and a
conductive film disposed between the pair of electrodes. A next
step includes covering a part of the first substrate with the
container, and thereby disposing the plurality of units within a
space formed between the first substrate and the container. Part of
the wires is disposed outside of the space. The method also
includes the steps of providing the space formed between the
container and the first substrate with a desired atmosphere,
converting each of the plurality of units to an electron emitting
device by applying a voltage to the plurality of units through the
part of the wires disposed outside of the space, removing the
container from the first substrate, and connecting a second
substrate including an image forming member to the first substrate,
via connecting member, at a region different from a region where
the container and the first substrate were connected together.
According to still another aspect, the present invention which
achieves these objectives relates to a further method for
manufacturing an image display device. The method includes a step
of disposing a first substrate on a supporting member, the first
substrate having mounted thereon a plurality of units, a plurality
of x-direction wires and a plurality of y-direction wires connected
to the plurality of units. Each unit includes a pair of electrodes
and a conductive film disposed between the pair of electrodes. A
next step includes covering a part of the first substrate with the
container, and thereby disposing the plurality of units within a
space formed between the first substrate and the container. Part of
the plurality of x-direction wires and the plurality of y-direction
wires is disposed outside of the space. The method also includes
the steps of providing the space formed between the container and
the first substrate with a desired atmosphere, converting each of
the plurality of units into an electron emitting device by applying
a voltage to the plurality of units through the part of the
plurality of x-direction wires and the plurality of y-direction
wires disposed outside of the space, removing the container from
the first substrate, and connecting a second substrate including an
image forming member to the first substrate via a connecting
member, at a region of the first substrate different from a region
where the container and the first substrate were connected
together.
An apparatus for manufacturing an electron-source substrate and an
image display device according to the present invention includes a
supporting member for supporting a substrate on which conductors
are formed, and a container covering the substrate supported by the
supporting member.
The container covers a part of the surface of the substrate, and
can thereby form an airtight space on the substrate in a state in
which part of wires formed on the substrate in a state of being
connected to the conductors is exposed outside the container. An
inlet and an outlet for a gas are provided at the container. Means
for guiding the gas into the container and means for exhausting the
gas from the container are connected to the inlet and the outlet,
respectively. It is thereby possible to set the inside of the
container to a desired atmosphere. An electron source is formed by
the substrate and electron emitting portions formed thereon
according to electric processing.
Accordingly, the above-described manufacturing apparatus also
includes means for performing electric processing, such as means
for applying a voltage to the conductors. In this manufacturing
apparatus, it is possible to reduce the size of the apparatus,
achieve a simple operability, for example, in electric connection
to a power supply in the electric processing, increase the degree
of freedom in the design of the size, the shape and the like of the
container, and perform introduction of the gas into the container
and exhaust of the gas to the outside of the container in a short
time.
In the manufacturing method, first, the substrate on which the
conductors and the wires connected to the conductors are formed is
disposed on the supporting member, and the conductors on the
substrate are covered with the container except for part of the
wires. Thus, the conductors are disposed in the airtight space
formed on the substrate in a state in which part of the wires
formed on the substrate is exposed outside of the container.
Then, the inside of the container is set to a desired atmosphere,
and electric processing is performed by, for example, application
of a voltage to the conductors through the part of the wires
exposed outside of the container. The desired atmosphere is, for
example, a low-pressure atmosphere, or an atmosphere in which a
specific gas is present. The electric processing causes the
electron source to be formed by forming the electron emitting
portions (which partially include the conductors). The electric
processing may be performed a plurality of times in different
atmospheres, depending on applicable design criteria.
For example, the conductors on the substrate are covered by the
container except for part of the wires. First, the step of
providing the inside of the container with a first atmosphere is
performed. Then, the step of providing the inside of the container
with a second atmosphere is performed. Thus, as a result, an
electron source is manufactured by forming electron emitting
portions in the conductors.
The first atmosphere preferably is a low-pressure atmosphere, and
the second atmosphere preferably is an atmosphere in which a
specific gas, such as a carbon compound or the like, is
present.
In the above-described manufacturing method, it is possible to
easily perform electric connection to the power supply in the
electric processing since part of the wires connected to the
conductors is disposed outside of the container. Since the degree
of freedom in the design of the size, the shape and the like of the
container is increased, it is possible to perform introduction of
the gas into the container and exhaust of the gas to the outside of
the container in a short time, improve the manufacturing speed, and
improve the reproducibility of the electron emission
characteristics of the manufactured electron source, particularly,
uniformity in the electron emission characteristics of the
plurality of electron emitting portions.
The electron-source substrate manufactured in the above-described
manner and another substrate having a phosphor formed thereon are
connected via a frame member using frit glass or the like so as to
maintain a constant interval between the two substrates.
Preferably, the region of the electron-source substrate where the
other substrate contacts the electron-source substrate is different
from the region where the container contacted the electron-source
substrate. Accordingly, the connection between the electron-source
substrate and the other substrate having the phosphor formed
thereon via the frame member is not influenced by adhesion of
components of a vacuum-tight member provided in the container when
connected to the electron-source substrate, and a stable connection
and reliable provision of a vacuum can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic perspective view illustrating the
configuration of an image forming apparatus with an upper portion
of the apparatus shown as being partially removed;
FIG. 1B is a cross-sectional view of the image forming apparatus
shown in FIG. 1A;
FIG. 2 is a cross-sectional view illustrating the configuration of
an apparatus for manufacturing an electron source according to the
present invention;
FIG. 3 is a perspective view illustrating a surrounding portion of
an electron-source substrate shown in FIGS. 2 and 4 with a portion
of that surrounding portion shown removed;
FIG. 4 is a cross-sectional view illustrating the configuration of
another apparatus for manufacturing an electron source according to
the present invention;
FIG. 5 is a cross-sectional view illustrating the configuration of
an apparatus for manufacturing an electron source which has a
sub-vacuum container, according to the present invention;
FIG. 6 is a cross-sectional view illustrating the configuration of
another apparatus for manufacturing an electron source which has a
sub-vacuum container, according to the present invention;
FIG. 7 is a cross-sectional view illustrating the configuration of
still another apparatus for manufacturing an electron source which
has a sub-vacuum container, according to the present invention;
FIG. 8 is a cross-sectional view illustrating the configuration of
yet another manufacturing apparatus according to the present
invention;
FIG. 9 is a perspective view illustrating the shape of a heat
conducting member used in an apparatus for manufacturing an
electron source according to the present invention;
FIG. 10 is a perspective view illustrating the shape of another
heat conduction member used in an apparatus for manufacturing an
electron source according to the present invention;
FIG. 11 is a cross-sectional view illustrating the configuration of
a heat conducting member using a rubber spherical substance which
is used in an apparatus for manufacturing an electron source
according to the present invention;
FIG. 12 is a cross-sectional view illustrating the configuration of
another heat conducting member using a rubber spherical substance
which is used in an apparatus for manufacturing an electron source
according to the present invention;
FIG. 13 is a cross-sectional view illustrating the shape of a
diffusing plate used in an apparatus for manufacturing an electron
source according to the present invention;
FIG. 14 is a cross-sectional view illustrating the shape of another
diffusing plate used in an apparatus for manufacturing an electron
source according to the present invention;
FIG. 15 is a plan view illustrating the configuration of an
electron emitting device according to the present invention;
FIG. 16 is a cross-sectional view of the electron emitting device
taken along line B-B' shown in FIG. 15;
FIG. 17 is a plan view illustrating an electron source according to
the present invention;
FIG. 18 is a plan view illustrating a method for manufacturing an
electron source according to the present invention;
FIG. 19A is a schematic perspective view illustrating the
configuration of an image forming apparatus with an upper portion
of the apparatus shown as having been removed; and
FIG. 19B is a cross-sectional view of the image forming apparatus
shown in FIG. 19A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A description will now be provided of a method for manufacturing an
image display device and a method for manufacturing an electron
source according to the present invention with reference to
schematic diagrams shown in FIGS. 1A, 1B, 2, 3 and 4. FIG. 1A is a
schematic perspective view of an image display device manufactured
according to the manufacturing method of the present invention. In
FIG. 1A, part of a face plate 66 and part of a supporting frame 62
are omitted for ease of display. FIG. 1B is a schematic
cross-sectional view taken along the x-z plane, illustrating the
image display device shown in FIG. 1A. FIGS. 2, 3 and 4 are
schematic diagrams illustrating an apparatus for manufacturing an
electron source (an electron-source substrate). FIGS. 2 and 4 are
cross-sectional views of the electron-source manufacturing
apparatus, and FIG. 3 is an enlarged perspective view of a
surrounding portion of a vacuum container 12. In FIGS. 1A, 1B, 2, 3
and 4, a member provided with the same reference numeral is the
same member.
The electron-source manufacturing apparatus is used at least in the
above-described "activating" process, and is preferably also used
in the above-described "forming" process.
In FIGS. 1A, 1B, 2, 3 and 4, there are shown x-direction wires 7,
y-direction wires 8, electron emitting devices 69, a rear plate (an
electron-source substrate) 10, a face plate 66 including a phosphor
film 64 and a conductive film (a metal back) 65 formed on an inner
surface of a transparent substrate 63, and a supporting frame 62
for providing a low-pressure space between the face plate 66 and
the rear plate 10. A terminal 67 is used for applying a high
voltage to the conductive film (metal back) 65. External
connections Dx1-Dxm are connected to corresponding ends 30 of the
x-direction wires 7, which extend from the space surrounded by the
rear plate 10, the supporting frame 62 and the face plate 66, to
outside of the frame 62, at portions outside of the low-pressure
space. External connections Dy1-Dyn are connected to corresponding
ends 30 of the y-direction wires 8, which extend from the space
surrounded by the rear plate 10, the supporting frame 62 and the
face plate 66, to outside of the frame 62, at portions outside of
the low-pressure space.
Reference numeral 61 represents a connection region (also referred
to herein as a "contact region") between the rear plate 10 and a
vacuum container 12 (a vacuum-tight member 18) (FIG. 2) used in the
"activating" process (to be described later). Reference numeral 71
represents a connection region (contact region) between the
supporting frame 62 (connection members 70) (FIG. 1B) and the rear
plate 10.
In this case, the connection region 61 between the vacuum container
12 (the vacuum-tight member 18) (FIGS. 2 and 3) and the rear plate
10 is disposed adjacent to an inside boundary of the connection
region 71 where the supporting frame 62 (the connection members 70)
contacts the rear plate 10. However, as shown in FIG. 19A, a
configuration of an image display device in which the connection
region 61 in which the vacuum container 12 (the vacuum-tight member
18) contacts the rear plate 10 is disposed outside the connection
region 71 (adjacent to an outer boundary of 71) in which the
supporting frame 62 (the connection members 70) contacts the rear
plate 10 may also be provided. FIG. 19B is a schematic
cross-sectional view taken along the xz plane of the image display
device shown in FIG. 19A.
That is, as will be described in detail later, the most important
point of the manufacturing method of the present invention is that
the connection region 61 in which the vacuum container 12 (the
vacuum-tight member 18) connects to the rear plate 10 differs from
the connection region 71 in which the supporting frame 62 (the
connection members 70) connects to the rear plate 10. According to
this configuration, it is possible to minimize a bad influence of
the residue of the vacuum-tight member 18 (which is used in order
to provide an airtight between the vacuum container 12 and the rear
plate 10) remaining on the rear plate 10 after being connected
between the rear plate 10 and the supporting frame 62. As a result,
it is possible to provide an air-tight contact between the
supporting frame 62 and the rear plate 10, and stably maintain a
high vacuum within the image display device for a long time.
In FIG. 3, a unit 6 includes a pair of electrodes and a conductive
film connecting the pair of electrodes. The unit 6 becomes an
electron emitting device by being subjected to the "forming"
process and the "activating" process which have been described
above.
In FIGS. 1A, 1B, 2, 3 and 4, there are shown the x-direction wires:
7, the y-direction wires 8, the rear plate 10, a supporting member
11 for supporting the rear plate 10, the vacuum container (cover)
12, a gas inlet 15, and a gas outlet 16. The x-direction wires 7
and the y-direction wires 8 are connected to the units 6. The
vacuum-tight member (hereinafter termed a "seal member") 18 is
provided between the rear plate 10 and the vacuum container 12 in
order to maintain a space surrounded by the rear plate 10 and the
vacuum container 12 in an airtight state. Preferably, the seal
member 18 is bonded to the vacuum container 12. The end portions 30
of the x-direction wires 7 and the y-direction wires 8 extend from
the space surrounded by the rear plate 10 and the vacuum container
12 to the outside of the overall device. A driver 32 includes a
power supply and a current control system. External wires 31
connect the end portions 30 of the x-direction wires 7 and the
y-direction wires 8 (not shown in FIG. 2) to the driver 32.
There are also shown a diffusing plate 19, apertures 33 in the
diffusing plate 19, temperature control means 20 for the rear plate
10, and a heat conducting member 41. Although the diffusing plate
19 is preferably provided so that a gas used for the "activation"
process and/or a gas used for the "forming" process are uniformly
supplied to the plurality of units 6, it is not always necessary to
employ that device 19. Although the temperature control means 20
and the heat conducting member 41 are preferably used when the area
(a region where the units 6 are provided) of the rear plate 10 is
large, they are not always necessary as well.
When using the above-described manufacturing apparatus for the
"forming" process, a reducing material (such as hydrogen or the
like) for the conductive film 65 of the unit 6 is selected as a
source gas 21. When using the electron-source manufacturing
apparatus for the "activating" process, a carbon compound material
is selected as the source gas 21.
Although a carrier gas 22 is used for the ease of introduction of
the source gas 21 into the vacuum container 12 whenever necessary,
it is not always necessary. Although filters 23 for removing water,
gas flow controllers 24, valves 25a-25f, a vacuum pump 26, a vacuum
gauge 27 and a tube 28 preferably are used whenever necessary, they
are no always necessary in other embodiments.
The supporting member 11 holds and fixes the rear plate 10, and
preferably has a mechanism for fixing the rear plate 10 by means of
a vacuum chuck mechanism, a fixing jig or the like (not shown). The
temperature control means 20, such as a heater or the like, is
preferably incorporated within the supporting member 11, and can
heat the rear plate 10 via heat conducting member 41 whenever
necessary. The heat conducting member 41 preferably is provided on
the supporting member 11. The heat conducting member 41 may be
grasped between the supporting member 11 and the rear plate 10, or
in other embodiments, no member 41 need be employed, as the
supporting member 11 itself may have the function of the heat
conducting member 41, so there is no obstacle to the holding and
fixing of the rear plate 10.
A viscous liquid substance, such as silicone grease, silicone oil,
a gel or the like, is preferably used as the heat conducting member
41. Such a deformable heat conducting member 41 can absorb warping
and undulation of the rear plate 10, and assuredly transmit heat
produced in a process of applying a voltage to the units 6 (the
"forming" process or the "activating" process) to the supporting
member 11 and a sub-vacuum container (to be described below) in
order to radiate the heat, prevent the generation of crack or
damage of the rear plate 10, and thereby contribute to improvement
in the production yield.
When there is the problem that the heat conducting member 41
comprising a viscous liquid substance (not shown) moves over the
supporting member 11, it is preferable to add a residence mechanism
on the supporting member 11 in accordance with the region on the
rear plate 10 where the units 6 are formed so that the viscous
liquid substance resides at predetermined positions and regions,
i.e., at least in the mentioned region. For example, an O-ring, or
a heat-resisting bag containing the viscous liquid substance to
provide a closed heat conducting member may be used as the
residence mechanism.
When causing the viscous liquid substance to reside by providing an
O-ring or the like, the viscous liquid substance sometimes
insufficiently contacts the supporting member 11 due to an air
layer formed between the viscous liquid substance and the
supporting member 11 In order to prevent such a problem, it is
preferable to adopt a configuration of providing threaded holes for
passing air, or a method of injecting the viscous liquid substance
between the supporting member 11 and the rear plate 10 after
placing the rear plate 10. FIG. 4 is a schematic diagram
illustrating an apparatus in which an O-ring and a
viscous-liquid-substance introducing tube are provided so that the
viscous liquid substance resides in a predetermined region.
The heat conducting member 41 may be an elastic member. For
example, a synthetic resin, such as a Teflon resin or the like, a
rubber material, such as silicone rubber or the like, a ceramic
material, such as alumina or the like, or a metal material, such as
copper, aluminum or the like, may be used as the material for the
elastic member. Such a material may be used in the form of a sheet
or a divided sheet. Alternatively, as shown in FIG. 9 or 10,
pillars in the form of a cylinder, a prism or the like, projections
in the form of a line, a cone or the like extending in the x
direction or the y direction, adapted to the interconnections on
the rear plate 10, round members in the form of a sphere, a rugby
ball (an elliptical sphere) or the like, spherical members in which
projections are formed on the surfaces of spheres, or the like may
be provided as the member 41 on the supporting member 11.
FIG. 11 is a schematic diagram illustrating the configuration of a
heat conducting member 41 using a plurality of spherical elastic
members. The heat conducting member 41 is formed by dispersing and
holding easily deformable fine spherical substances made of rubber
or the like, and spherical substances having diameters smaller than
the diameters of the fine spherical substances (which are less
deformable than the rubber), between the electron-source substrate
10 and the supporting member 11.
FIG. 12 is a schematic diagram illustrating the configuration of a
heat conducting member 41 made of a composite material. A spherical
central member of the member 41 is formed by a hard material, such
as a ceramic material, metal or the like. The heat conducting
member 41 is provided by substances obtained by coating the
surfaces of the spherical central members with rubber. When using,
for example, spherical substances easily movable on the supporting
member 11, a configuration in which a residence mechanism is
provided on the supporting member 11 as described in the case of
using a viscous liquid material is desirable.
Projections and recesses may be formed on the surface of an elastic
heat conducting member 41 facing the electron-source substrate 10.
The projections and recesses preferably have the above-described
shape of pillars, lines, projections, spheres (semi-spheres) or the
like. More specifically, linear projections and recesses
substantially adapted to the x-direction or y-direction
interconnections on the electron-source substrate 10, as shown in
FIG. 9, or pillar projections substantially adapted to the
positions of respective electrodes, as shown in FIG. 10, are
preferable. Alternatively, although not illustrated, it is
preferable that semispherical projections are formed on the surface
of the heat conducting member 41.
By disposing the heat conducting member 41 in the above-described
manner, it is possible to promptly and assuredly radiate heat in
the process of applying a voltage to the respective units 6 (the
"forming" process or the "activating" process). It also is possible
to contribute to reduction of the density distribution of the
introduced gas due to the temperature distribution, and reduction
of non-uniformity of electron emitting devices due to the heat
distribution of the substrate, and allow manufacture of a very
uniform electron source.
For example, a closed tube (not shown) in which a
temperature-control medium is sealed may be adopted as the
temperature control means 20. Although not illustrated, a
mechanism, in which the above-described viscous liquid substance is
held between the supporting member 11 and the rear plate 10 and is
circulated while performing temperature control, may be used as
heating means or cooling means for the rear plate 10. Temperature
control for a target temperature can also be performed. For
example, a mechanism (not shown) including a circulating
temperature control device, a liquid medium and the like may also
be used.
The vacuum container (cover) 12 is made of glass or stainless
steel. The vacuum container (cover) 12 covers the rear plate 10 so
that a partial region (the end portions of the x-direction
interconnections 7 and the y-direction interconnections 8) on the
surface of the rear plate 10 is exposed to the atmospheric air.
More specifically, as shown in FIG. 3, a region where the units 6
on the rear plate 10 are formed is contained in the space
surrounded by the vacuum container 12 and the rear plate 10. On the
other hand, in a region on the surface of the rear plate 10 which
is not surrounded by the vacuum container 12 and the rear plate 10,
the end portions of the x-direction interconnections 7 and the
y-direction interconnections 8 are exposed to the atmospheric air.
According to such a configuration, it is possible to easily perform
application of a voltage to each of the units 6 in the "activating"
process or the "forming" process via the end portions 30 of the
interconnections 7 and 8 which are exposed to the atmospheric
air.
The vacuum container 12 is preferably configured so as to be able
to endure at least a pressure range between 1.33.times.10.sup.-1 Pa
(1.times.10.sup.-3 Torr) and the atmospheric pressure.
The seal member 18 (FIG. 2) is an elastic member used for
maintaining air tightness between the rear plate 10 and the vacuum
container 12. Preferably, the elastic member is made of rubber, and
is embodied as an O-ring or a rubber sheet made of nitrile rubber,
silicone rubber, fluororubber or the like.
An organic gas, or a gas obtained by diluting an organic gas by an
inert gas, such as nitrogen, helium, argon or the like, is used as
the carbon-compound gas used in the "activating" process.
When performing the "forming" process (to be described later), it
is preferable to introduce a gas for accelerating formation of a
gap in the conductive film, such as a gas for reducing the
conductive film (preferably, a hydrogen gas or the like) 65, into
the vacuum container 12.
An organic substance to be used in the "activating" process of the
electron emitting device preferably is selected from aliphatic
hydrocarbons, such as alkane, alkene, alkyne and the like, aromatic
hydrocarbons, alcohols, aldehydes, ketones, amines, nitrites,
phenol, organic acids, such as carboxylic acid, sulfonic acid and
the like. More particularly, a saturated hydrocarbon represented by
a composition formula of C.sub.n H.sub.2n+2, such as methane,
ethane, propane or the like, an unsaturated hydrocarbon represented
by a composition formula of C.sub.n H.sub.2n, such as ethylene,
propylene or the like, benzene, toluene, methanol, ethanol,
acetaldehyde, acetone, methyl ethyl ketone, methylamine,
ethylamine, phenol, benzonitrile, acetonitrile or the like
preferably may be used.
When the organic substance to be used is a gas at room temperature,
the substance can be directly used. On the other hand, when the
organic substance to be used is a liquid or a solid at room
temperature, the substance preferably is used by being evaporated
or sublimated within a container.
When using the above-described carrier gas 22, the organic gas 21
and the carrier gas 22 are mixed at a constant ratio, and the gas
mixture is introduced into the vacuum container 12. The flow rate
and the mixture ratio of the organic gas 21 and the carrier gas 22
are controlled by gas-flow controllers 24. The gas-flow controller
24 preferably includes a mass flow controller, an electromagnetic
valve or the like. The gas mixture is heated to an appropriate
temperature by a heater (not shown) provided around the tube 28 if
necessary, and is then guided into the vacuum container 12 through
the inlet 15. The heating temperature of the gas mixture preferably
is substantially equal to the temperature of the electron-source
substrate 10.
It is preferable to provide the water removing filters 23 at
portions upstream from the tube 28 in order to remove water in the
introduced gas. A moisture absorbent, such as silica gel, a
molecular sieve, magnesium hydroxide or the like, may be used for
the water removing filter 23.
The gas introduced into the vacuum container 12 is exhausted at a
constant pumping speed by the vacuum pump 26 via the exhaust outlet
16, and the pressure of the gas mixture within the vacuum container
12 preferably is maintained to a constant level. The vacuum pump 26
used in the invention preferably is a rough vacuum pump, such as a
dry pump, a diaphragm pump, a scroll pump or the like, although in
a preferred embodiment an oil-free pump preferably is used.
Although it depends on the type of the organic substance to be used
in the "activating" process, it is preferable to use a gas in a
so-called viscous-flow region in order to more easily perform the
"activating" process in this manufacturing apparatus. In the
"viscous-flow region", the pressure has at least a value at which
the mean free path .lambda. of the gas (the organic gas, or the gas
mixture of the organic gas and the carrier gas) introduced into the
vacuum container 12 is sufficiently smaller than the size of the
inside of the vacuum container 12. More specifically, the pressure
preferably is between several hundreds of Pa (several Torrs) and
the atmospheric pressure.
By providing the diffusing plate 19 between the gas inlet 15 of the
vacuum container 12 and the electron-source substrate 10, the flow
of the gas introduced into the vacuum container 12 is controlled,
so that the organic substance can be supplied uniformly on the
entire surface of the substrate (rear plate) 10. As a result, the
uniformity of the electron emitting devices is improved. Hence, the
diffusing plate 19 preferably is used. As shown in FIGS. 2 and 4,
for example, a metal plate having a plurality of apertures 33 is
used as the diffusing plate 19. As shown in FIG. 13 or 14, the
apertures 33 of the diffusing plate 19 are preferably formed by
changing the area or the number from a portion near the inlet 15 to
a portion remote from the inlet 15.
In the diffusing plate 19, if the apertures 33 are formed such that
the aperture area is larger as the aperture is more separated from
the inlet as shown in FIG. 14, or although not shown, that the
number of apertures 33 in the plate 19 is larger, or the aperture
area is larger and the number of apertures in the plate 19 is
larger as the aperture is more separated from the inlet 15, the
flow rate of the gas mixture flowing in the vacuum container 12
becomes substantially constant. Hence, such a configuration is more
preferable from the viewpoint of improving the uniformity. However,
it is important that the diffusing plate 19 have a shape for which
the characteristics of the viscous flow are taken into
consideration. It should be noted that the shape of the diffusing
plate 19 is not limited to the shapes described in this
specification.
For example, in one embodiment the apertures 33 may be
concentrically formed with an equal interval and with an equal
angular interval in the circumferential direction so that the area
of each aperture satisfies the relationship represented by formula
F1 below. In this case, the apertures 33 are designed so that the
area of each aperture increases in proportion to the distance form
the inlet of the substrate. It is thereby possible to very
uniformly supply the surface of the electron-source substrate 10
with the introduced substance, and uniformly activate the electron
emitting devices.
where d is the distance from an intersection made by an imaginary
line from the center of the gas inlet 15 and the diffusing plate
19, L is the distance from the center of the gas inlet 15 to an
intersection between an imaginary line extending from the center of
the gas inlet 15 and the diffusing plate 19, Sd is the area of an
aperture at the distance d from the intersection made by the
prolonged line from the center of the gas inlet 15 and the
diffusing plate 19, and S.sub.0 is the area of an aperture at the
intersection between an imaginary line extending from the center of
the gas inlet 15 to the diffusing plate 19.
The positions of the gas inlet 15 and the exhaust outlet 16 are not
limited to those referred to above, but those elements 15 and 16
may have various other positions. However, in order to uniformly
supply the organic substance into the vacuum container 12, the
positions of the gas inlet 15 and the exhaust outlet 16 are
preferably at upper positions in the vacuum container 12 as shown
in FIG. 2 or 4, or at left and right positions substantially
symmetrically as shown in FIG. 7.
As described above, the end portions 30 of the x-direction wires 7
and the y-direction wires 8 are outside the vacuum container 12.
The end portions 30 are connected to the driver 32 via a TAB
(tape-automated bonding) wire, a probe or the like.
In the case of this manufacturing apparatus, since it is necessary
to cover only the respective units 6 with the vacuum container 12
in the above-described manner, it is possible to reduce the size of
the manufacturing apparatus. That is, the size of the manufacturing
apparatus can be reduced relative to conventional manufacturing
apparatuses in which an entire substrate (rear plate) is placed
within a vacuum chamber. When performing the "activating" process
and the "forming" process after sealing a face plate where an image
forming member, such as a phosphor or the like, is disposed and a
rear plate on which the units 6 are disposed as in the conventional
approach, the conductance is reduced because the separation between
the face plate and the rear plate is small, and a long time is
required for introducing and exhausting a gas. However, according
to the manufacturing method using the manufacturing apparatus of
the invention, since the vacuum container 12 having a large volume
(a large conductance) covers only a region on the rear plate 10
where the units 6 are disposed, and introduction of a gas into, and
exhaust of the gas from, the vacuum container 12 are performed in
this state, the amount of time required for the "activating"
process and the "forming" process can he greatly reduced relative
to that in the conventional technique. Furthermore, since the
volume of the vacuum container 12 can be increased, it is possible
to very uniformly supply the respective units 6 on the rear plate
(the electron-source substrate) 10 with an organic gas or a
reducing gas, and, as a result, to form very uniform electron
emitting devices. Since the end portions 30 of the x-direction
wires 7 and the y-direction wires 8 on the electron-source
substrate (rear plate) 10 are outside the vacuum container 12, it
is possible to easily perform electrical connection with a power
supply device (driver) for applying a voltage to the respective
units 6 in the atmospheric air.
By applying a pulse voltage to each of the units 6 on the rear
plate through the x-direction wires 7 and the y-direction wires 8
using the driver 32 in a state in which an organic gas is flown
into the vacuum container 12 in the above-described manner, the
"activating" process for the electron emitting devices can be
performed.
Similarly, the above-described "forming" process can be performed
by using a reducing gas, such as hydrogen or the like, instead of
the organic gas. It is, of course, possible to perform the
"forming" process by placing the respective units 6 merely in a
vacuum without using the above-described vacuum container 12
(manufacturing apparatus) instead of using the reducing gas.
A description will now be provided of other manufacturing
apparatuses obtained by changing a part of the above-described
manufacturing apparatus. A main change in these apparatuses is the
method for supporting the electron-source substrate 10. Other
portions are the same as in the above-described apparatus. FIGS. 5
and 6 illustrates such manufacturing apparatuses.
In FIGS. 5 and 6, there are shown a vacuum container 12, a
sub-vacuum container 14, and an exhaust outlet 17 for the
sub-vacuum container 14. The same components as those shown in
FIGS. 2-4 are indicated by the same reference numerals.
When the size of the electron-source substrate 10 is large, in
order to prevent damage of the electron-source substrate 10 due to
the pressure difference between the surface side and the back side
of the electron-source substrate 10, i.e., between the pressure
within the vacuum container 12 and the atmospheric pressure, the
pressure difference can be mitigated by increasing the thickness of
the electron-source substrate 10 to a value so as to be able to
endure the pressure difference, or by also using a vacuum chucking
method for the electron-source substrate 10.
In these apparatuses, it is intended to cause the pressure
difference across the electron-source substrate (rear plate) 10 to
disappear or to have a negligibly small value, so that the
electron-source substrate 10 can be more thin. When applying this
electron-source substrate 10 to an image forming apparatus, the
weight of the image forming apparatus can be reduced. In these
apparatuses, the electron-source substrate 10 is held between the
vacuum container 12 and the sub-vacuum container 14. By maintaining
the pressure within the sub-vacuum container 14 replacing the
supporting member 11 to a value substantially equal to the pressure
within the vacuum container 12, the electron-source substrate 10 is
maintained so that it lies in a substantially horizontal plane.
The pressures within the vacuum container 12 and the sub-vacuum
container 14 are measured by vacuum gauges 27a and 27b,
respectively. By adjusting the amount of opening of a valve 25g of
the exhaust outlet of the sub-vacuum container 14, it is possible
to make the pressures within the two vacuum containers 12 and 14
substantially the same.
In FIG. 5, a sheet-like first heat conducting member 41
manufactured with the same material as that of the seal member 18,
and a metal second heat conducting member 42 having a large heat
conductivity in order to more efficiently radiate heat from the
electron-source substrate 10 to the outside via the first heat
conducting member 41 and the sub-vacuum container 14 are provided
within the sub-vacuum container 14 as heat conducting members for
the electron-source substrate 10.
In FIG. 6, the first heat conducting member 41, and a third heat
conducting member 43 made of a metal elastic material having a
large heat conductivity in order to more efficiently radiate heat
from the electron-source substrate 10 to the outside via the heat
conducting member 41 and the sub-vacuum container 14 are
provided.
In FIGS. 5 and 6, in order to facilitate understanding the outline
of the apparatuses, the thickness of the sub-vacuum container 14 is
shown to be larger than the actual thickness.
A heater (not shown) is embedded within the second heat conducting
member 42 so as to be able to heat the electron-source substrate
10, and can be subjected to temperature control from the outside by
a control mechanism (not shown).
In still another configuration, a tube-like closed container (not
shown) so as to be able to hold or circulate a liquid may be
incorporated within the second heat conducting member 42 (FIG. 5).
By controlling the temperature of the liquid from the outside, the
electron-source substrate 10 can be cooled or heated via the first
heat conducting member 41. It also is possible to provide a heater
(not shown) at a base portion of the sub-vacuum container 14 or
embed a heater (not shown) within a base portion of the sub-vacuum
container 14, provide an external control mechanism (not shown) for
performing temperature control from the outside, and heat the
electron-source substrate 10 via the second heat conducting member
42 and the first heat conducting member 41. Alternatively, it also
is possible to provide the above-described heating means (not
shown) within the second heat conducting member 42 and at the
sub-vacuum container 14, and perform temperature control such as
heating, cooling or the like, for the electron-source substrate
10.
Although in the above-described configurations, two different types
of heat conducting members 41 and 42 preferably are used, the
number of types is not limited to two, but may be one or at least
three or more.
The positions of the gas inlet 15 and the exhaust outlet 16 are not
limited to those described above, but may be various other
positions. However, in order to uniformly supply the organic
substance into the vacuum container 12, the positions of the gas
inlet 15 and the exhaust outlet 16 are preferably at upper
positions in the vacuum container 12 as shown in FIG. 5 or 6, or at
left and right positions substantially symmetrically as shown in
FIG. 7.
In these configurations, as in the foregoing configuration, when
there is a process of introducing a gas into the vacuum container
12, it is preferable to use the diffusing plate 19 in the same
manner as described above. As in the foregoing configuration, the
forming process can be performed, and the activating process for
the electron emitting devices can also be performed by applying a
pulse voltage to each of the electron emitting devices 6 on the
electron-source substrate 10 via the interconnection 31 by using
the driver 32 while flowing the gas mixture containing the organic
substance into the container 12.
A manufacturing apparatus having a still another configuration will
now be described with reference to FIG. 8. In this configuration,
in order to prevent deformation or damage of a substrate 10 due to
the above-described pressure difference between the surface and the
back of the substrate 10, an electrostatic chuck 208 is provided at
a substrate holder 207. Fixing of the substrate 10 by the
electrostatic chuck is realized by attracting the substrate 10 to
substrate holder 207 by an electrostatic force produced by applying
a voltage between an electrode 209 and the substrate 10 placed in
the electrostatic chuck 208. There are also shown an O-ring 203,
benzonitrile 204, a vacuum gauge 205, an evacuation system 206, a
probe unit 215, and a pulse generator 216.
In order to maintain a predetermined potential on the substrate 10,
a conductive film (not shown), such as an ITO (indium tin oxide)
film or the like, is formed on the back of the substrate 10. For
attracting the substrate 10 according to the electrostatic chuck
method, the distance between the electrode 209 and the substrate 10
must be short. Hence, it is desirable to first press the substrate
10 against the electrostatic chuck 208 according to another method
In the apparatus shown in FIG. 8, the substrate 10 is pressed
against the electrostatic chuck by the atmospheric pressure by
evacuating the inside of grooves 211 formed on the surface of the
electrostatic chuck 208, and the substrate 10 is sufficiently
attracted by applying a high voltage to the electrode 209 from a
voltage power supply 210.
Even if the inside of a vacuum chamber 202 is thereafter evacuated,
the pressure difference applied to the substrate 10 is cancelled
due to an electrostatic force by the electrostatic chuck 208, so
that it is possible to prevent deformation or damage of the
substrate 10.
In order to improve heat conduction between the electrostatic chuck
208 and the substrate 10, it is desirable to introduce a gas for
heat exchange into the grooves 211 after first evacuating them as
described above. Although He is desirable as the gas, any other gas
is also effective. By introducing the gas for heat exchange, heat
conduction between the substrate 10 and the electrostatic chuck 208
at a portion where the grooves 211 are present is realized. Even at
a portion where the grooves 211 are absent, since heat conduction
is improved relative to a case in which there is thermal contact
between the substrate 10 and the electrostatic chuck 208 merely by
mechanical contact, heat conduction as a whole is substantially
improved. According to the above-described configuration, heat
generated at the substrate 10 easily moves to the substrate holder
207 via the electrostatic chuck 208 during the forming process, the
activating process or the like, so that generation of an undesired
temperature distribution due to an undesired temperature rise of
the substrate 10 or local heat generation is suppressed.
Furthermore, by providing temperature control means, such as a
heater 212, a cooling unit 213 and the like, at the substrate
holder 207, the temperature of the substrate 10 can be very
precisely controlled.
EXAMPLE 1
A process for manufacturing an electron-source substrate shown in
FIG. 17 including a plurality of surface-conduction-type electron
emitting devices shown in FIGS. 15 and 16, using the
above-described manufacturing apparatus of the present invention
will now be more specifically described.
In FIGS. 15-17, there are shown a substrate (rear plate) 10,
electrodes 2 and 3, a conductive film 4, a carbon film 29, a gap 5
in the carbon film 29, and a gap G in the conductive film 4.
First, a Pt paste was subjected to printing on a glass substrate
(having a size of 350.times.300 mm, and a thickness of 5 mm) having
a SiO.sub.2 layer formed thereon, according to offset printing. The
printed film was baked to form the electrodes 2 and 3 having a
thickness of 50 nm as shown in FIG. 16. Then, an Ag paste was
subjected to printing according to screen printing. The printed
film was baked to form x-direction wires 7 (240 in total) and
y-direction wires (20 in total) 8 shown in FIG. 17. An insulating
paste was subjected to printing according to screen printing on
intersections made by the x-direction wires 7 and the y-direction
wires 8. The printed film was baked to form an insulating layer
9.
Then, a palladium-complex solution was provided onto each portion
between the electrodes 2 and 3 according to an inkjet method.
Although a bubble-jet-type apparatus was used as an inkjet
apparatus, a so-called piezoelectric ink-jet apparatus may also be
used. The conductive film 4 made of palladium oxide was formed by
baking droplets provided on the substrate 10 at 350.degree. C. for
30 minutes. The thickness of the conductive film 4 was 20 nm. Thus,
a plurality of units 6, each including the pair of electrodes 2 and
3 and the conductive film 4, were formed on the substrate (rear
plate) 10. The units 6 were connected in the form of a matrix by
the x-direction wires 7 and the y-direction wires 8. Thus, the
electron-source substrate 10 before the "forming" process was
formed.
The electron-source substrate 10 manufactured in the
above-described process was fixed on the supporting member 11 of
the manufacturing apparatus shown in FIGS. 2 and 3. A heat
conductive rubber sheet 41 having a thickness of 1.5 mm was grasped
between the supporting member 11 and the electron-source substrate
10.
Then, the stainless-steel vacuum container 12 was disposed on the
electron-source substrate 10 as shown in FIG. 3 via the seal member
18 made of silicone rubber, such that the end portions 30 of the
x-direction wires 7 and the y-direction wires 8 were outside of the
vacuum container 12 (and exposed to the atmospheric air). A metal
plate in which the apertures 33 as shown in FIG. 13 or 14 are
formed, was provided above the electron-source substrate 10 as the
diffusing plate 19.
After opening the valve 25f (FIG. 2) for the exhaust outlet 16, and
evacuating the inside of the vacuum container 12 to about
33.times.10.sup.-1 Pa (1.times.10.sup.-3 Torr) by the vacuum pump
26 (a scroll pump in this case), in order to remove water estimated
to adhere to the tube of the evacuation apparatus and the
electron-source substrate 10, a baking process of raising the
temperature of the substrate 10 to 120.degree. C. using a heater
(not shown) for the tube and the heater 20 for the electron-source
substrate 10, and cooling the temperature to the surrounding room
temperature after maintaining the above-described temperature was
performed.
After the temperature of the substrate 10 returned to the room
temperature, the gap G shown in FIG. 16 was formed in the
conductive film 4 by passing a current in the conductive film 4 by
applying a voltage between the electrodes 2 and 3 of each of the
units 6 via the x-direction wires 7 and the y-direction wires 8
using the driver 32 connected to the end portions 30 via the wires
31 shown in FIG. 3 (the "forming" process).
Then, the "activating" process was performed using the same
apparatus. The gas mixture of the organic gas 21 and the carrier
gas 22 was introduced into the vacuum container 12 by opening the
valves 25a-25d for supplying the gases and opening the valve 25e
for the air inlet 15 shown in FIG. 2. An ethylene gas was used as
the organic gas 21, and a nitrogen gas was used as the carrier gas
22. The pressure within the vacuum container 12 was set to a
desired pressure by adjusting the amount of opening of the valve
26f while watching the pressure of the vacuum gauge 27 at the
exhaust outlet 16.
After introducing the organic gas, the "activating" process was
performed by applying a pulse voltage between the electrodes 2 and
3 of each of the units 6 via the x-direction wires 7 and the
y-direction wires 8 using the driver 32. In the "activating"
process, the entirety of the y-direction wires 8 and unselected
lines of the x-direction wires 8 were commonly connected to Gnd
(ground potential), and a pulse voltage was sequentially applied to
each line by selecting a desired one of the x-direction wires
7.
A device current If (a current flowing between the electrodes of an
electron emitting device) when completing the activating processing
was measured for each of the x-direction wires 7. A result of
comparison of measured values of the device current If indicated
that variations among the x-direction wires 7 were small, and
therefore a successful and advantageous activating process could
been performed.
As shown in FIGS. 15 and 16, carbon films 29 were formed across the
gap 5 in the electron emitting device after completing the
activating process.
EXAMPLE 2
Next, an example of manufacturing an electron-source substrate
using the manufacturing apparatus shown in FIG. 5 will be
described.
An electron-source substrate before the "forming" process was
manufactured in the same manner as in Example 1 by using a glass
substrate comprised of SiO.sub.2 3 and being mm thick, as the rear
plate 10 (see FIG. 18). This electron-source substrate 10 was
placed between the vacuum container 12 and the sub-vacuum container
14 of the manufacturing apparatus shown in FIG. 5 via the seal
member 18 made of silicone rubber with a sheet-like heat conducting
member 41 made of silicone rubber having column-shaped projections
on a surface contacting the electron-source substrate 10, and a
heat conduction member 42 made of aluminum having an embedded
heater (not shown) therewithin, in the manner shown in FIG. 5.
In Example 2, however, in contrast to the case shown in FIG. 5, the
"activating" process was performed without providing the diffusing
plate 19.
The inside of the vacuum container 12 and the inside of the
sub-vacuum container 14 were evacuated by vacuum pumps (scroll
pumps in this case) 26a and 26b, respectively, by opening a valve
25f for the exhaust outlet 16 of the vacuum container 12 and the
valve 25g for the exhaust outlet 17 of the sub-vacuum container
14.
Evacuation was performed while maintaining the pressure within the
vacuum container 12 so that it was greater than or equal to the
pressure within the sub-vacuum container 14. According to this
condition, when the substrate 10 is deformed to produce a strain
due to the pressure difference, the substrate 10 becomes convex
relative to the sub-vacuum container 14 to be pressed against the
heat conducting member 41, which suppresses the deformation and
supports the substrate 10.
If the size of the electron-source substrate 10 is large and the
thickness of the electron-source substrate 10 is small, and if a
condition opposite to that described above is present, i.e., the
pressure within the vacuum container 12.ltoreq. the pressure within
the sub-vacuum container 14, then when the electron-source
substrate 10 becomes convex relative to the vacuum container 12,
the electron-source substrate 10 may become damaged (in the worst
case) because there is no member for suppressing the deformation of
the substrate 10 in that direction, resulting from the pressure
difference, and for supporting the electron-source substrate 10
within the vacuum container 12. That is, in the electron-source
manufacturing apparatus shown in FIG. 5, as the size of the
electron-source substrate 10 is larger and the thickness of the
electron-source substrate 10 is smaller, the heat conducting member
41 also operating as the substrate holding member becomes more
important.
Then, as in Example 1, the gap G shown in FIG. 16 was formed in the
conductive film 4 by passing a current by applying a voltage
between the electrodes 2 and 3 of each of the units 6 via the
x-direction wires 7 and the y-direction wires 8 using the driver 32
(the "forming" process). In this manufacturing method, a hydrogen
gas for reducing palladium oxide was gradually introduced
simultaneously with a start of voltage application, in order to
accelerate formation of the gap G in the conductive film 4.
Then, the "activating" process was performed using the same
apparatus. The gas mixture of the organic gas 21 and the carrier
gas 22 was introduced into the vacuum container 12 by opening the
valves 25a-25d for supplying the gases and the valve 25e for the
gas inlet 15. A propylene gas was used as the organic gas 21, and a
nitrogen gas was used as the carrier gas 22. The gas mixture was
introduced into the vacuum container 12 after being passed through
the respective water removing filters 23. The pressure within the
vacuum container 12 was set to a desired pressure by adjusting the
amount of opening of the valve 25f while watching the pressure of
the vacuum gauge 27 for the exhaust outlet 16.
At the same time, the pressure within the sub-vacuum container 14
was set to be lower than the pressure within the vacuum container
12 by adjusting the amount of opening of the valve 25g for the
exhaust outlet 17 of the sub-vacuum container 14.
Then, as in Example 1, the "activating" process was performed by
applying a voltage between the electrodes 2 and 3 of each of the
units 6 via the x-direction wires 7 and the y-direction wires 8
using the driver 32. A device current (a current flowing between
the electrodes 2 and 3) If present during the activating processing
was measured in the same manner as in Example 1. The result of the
measurement indicated that variations in the current in the devices
were small, and therefore an excellent and improved activating
process could been performed.
As shown in FIGS. 15 and 16, carbon films 29 were formed across the
gap 5 in the electron emitting device after completing the
activating process.
In this manufacturing process, since the gas mixture containing the
organic substance was introduced into the vacuum container 12 at a
viscous-flow region having a pressure of 266.times.10.sup.2 Pa (200
Torr), the organic substance within the vacuum container 12 could
be made constant in a short time. As a result, the time required
for the activating process could be largely shortened
EXAMPLE 3
In Example 3, the electron-source substrate 10 manufactured by the
manufacturing apparatus and the manufacturing process described in
Example 1 and Example 2 was used for the image display device shown
in FIGS. 1A and 1B.
FIG. 1A is a schematic diagram illustrating the image display
device manufactured in Example 3, and FIG. 1B is a cross-sectional
view of the device taken along the x-z plane.
In FIG. 1A, there are shown the electron emitting devices 69, and
the supporting frame 62. The faceplate 66 includes the glass
substrate 63, the metal back 64 and the phosphor 65. There is also
shown the high-voltage terminal 67. Reference numeral 61 represents
a trace of connection of the seal member 18 remaining after the
vacuum container 12 (not shown in FIGS. 1A and 1B) was mounted on
the electron-source substrate 10 and then removed together with the
seal member 18 in the electron-source-substrate manufacturing
process.
As shown in FIG. 1B, connection members 70 made of frit glass, an
indium alloy or the like are grasped between the electron-source
substrate 10 and the supporting frame 62, and between the faceplate
66 and the supporting frame 62.
The connection position 71 between the electron-source substrate 10
and the supporting frame 62 was arranged to be outside the contact
region 61 of the seal member 18 so as not to overlap therewith. In
the connection region 61, a part of an O-ring or a rubber sheet
made of nitrile rubber, silicone rubber, fluororubber or the like,
serving as the seal member 18, sometimes remains as a residue as a
result of being pressed against the electron-source substrate 10 or
heat treatment of the electron-source substrate 10. As a result,
the surface state of the electron-source substrate 10 sometimes
greatly changes, represented by, for example, a decrease in the
wettability at the contact region 61. Accordingly, when intending
to perform connection between the supporting frame 62 and the
electron-source substrate 10 at the contact region 61, an
insufficient connection sometimes occurs as a result of the
residue, thereby sometimes causing vacuum leakage when evacuating
the inside of the image display device, as will be described below.
Hence, in the present invention, connection between the supporting
frame 62 and the electron-source substrate 10 is performed at a
region (the contact position 71) different from the contact region
61.
The arrangement of the contact position 71 outside the contact
region 61 of the seal member 18 contributes to reduction in the
size of the vacuum container 12.
The inside of the image display device is maintained in a
low-pressure state. The image display device as shown in FIGS. 1A
and 1B is manufactured by evacuating the inside of the image
display device, for example, via an exhaust tube (not shown)
provided at the faceplate 66 to maintain the inner pressure to a
value less than the atmospheric pressure, and then sealing the
exhaust tube. In order to maintain the pressure within the image
display device after sealing, a getter material (not shown) is
sometimes provided within the image display device and is subjected
to high-frequency heating.
In the image display device manufactured in the above-described
manner, the vacuum state within the image display device can be
maintained in a desired condition. An image is displayed by
emitting an electron from each electron emitting device by applying
a scanning signal and a modulating signal from a signal generation
means (not shown) via the terminals Dx1-Dxm, and Dy1-Dyn, and
accelerating an emitted electron beam by applying a high voltage of
5 kV to the metal back 65 or a transparent electrode (not shown)
via the high-voltage terminal 67 to cause the electron beam to
impinge upon the phosphor film 64, thereby exciting the phosphor to
emit light.
In the image display apparatus manufactured in the above-described
manner, an excellent image is provided in which variations in the
luminance and irregularity in color are minimized, thereby
rendering the apparatus highly suitable for use as a
television.
EXAMPLE 4
Example 4 will now be described with reference to FIGS. 19A and
19B. FIG. 19A is a schematic perspective view illustrating an image
display device manufactured in Example 4. FIG. 19B is a schematic
cross-sectional view taken along the x-z plane of FIG. 19A. In
FIGS. 19A and 19B, the same components as those shown in FIGS. 1A
and 1B are indicated by the same reference numerals.
In Example 4, the contact position 71 between the electron-source
substrate 10 and the supporting frame 62 manufactured in Example 1
or Example 2 is arranged so as to be within the contact region 61
of the seal member 18 (so as not overlap therewith). The image
display device was otherwise manufactured in the same manner as in
Example 3. In Example 4, since the size of the faceplate 66 can be
reduced and the trace of region 61 on the electron-source substrate
10 is outside a portion where a vacuum is formed, the influence of
gases emitted from the trace of region 61 on the electron source
need not be considered.
As in the image display device manufactured in Example 3, an image
which is excellent and stable for a long time could be obtained in
the image display device manufactured in Example 4.
According to the present invention, it is possible to provide a
method for manufacturing an image display device which is adapted
for being mass produced with an increased manufacturing speed
relative to those of the prior art.
According to the present invention, it is possible to provide a
method for manufacturing an image display device in which an
electron source having excellent electron emission characteristics
can be manufactured.
According to the present invention, it is possible to provide an
image display device having an excellent image quality by forming
stable vacuum tightness.
The individual components shown in outline in the drawings are all
well known in the image-display-device manufacturing method arts
and their specific construction and operation are not critical to
the operation or the best mode for carrying out the invention, and
thus will not be described in further detail herein.
While the present invention has been described with respect to what
are presently considered to be the preferred embodiments, it is to
be understood that the invention is not limited only to the
disclosed embodiments. To the contrary, the present invention is
intended to cover various modifications and equivalent arrangements
included within the spirit and scope of the appended claims. The
scope of the following claims is to be accorded the broadest
reasonable interpretation so as to encompass all such modifications
and equivalent structures and functions.
* * * * *